The long-term goal of this project is to develop a non-invasive, noise-based technique for enhancing somatosensation and thereby improving balance control in elderly individuals and patients with somatosensory deficits. In previous studies, we have shown that sub-sensory mechanical noise (i.e., random vibration with a small intensity) can enhance somatosensory function in healthy individuals and older adults with somatosensory deficits. Moreover, we have shown that the postural sway of both healthy young and healthy elderly individuals during quiet standing can be significantly reduced by applying sub-sensory mechanical noise to the feet using vibrating shoe insoles. Despite these promising results, we still need to determine whether the intervention is effective in improving dynamic balance control and clinical measures of balance in addition to quiet-standing balance control, whether subjects adapt to the input noise that is used as part of the intervention, and in which types of patients this intervention is effective. Thus, in this project, we plan to build upon this work and explore the effects of our noise-based technique on biomechanical and clinical measures of balance in healthy elderly individuals, diabetic patients with somatosensory deficits, and stroke patients with somatosensory deficits. The specific aims of this project are: (1) to determine the effects of noise-enhanced somatosensation at the feet on balance performance in healthy elderly individuals; (2) to assess whether adaptation occurs in noise-enhanced balance control in healthy elderly individuals; (3) to determine the effects of noise-enhanced somatosensation at the feet on balance performance in diabetic patients with somatosensory deficits; (4) to assess whether adaptation occurs in noise-enhanced balance control in diabetic patients with somatosensory deficits; (5) to determine the effects of noise-enhanced somatosensation at the feet on balance performance in stroke patients with somatosensory deficits; and (6) to assess whether adaptation occurs in noise-enhanced balance control in stroke patients with somatosensory deficits. To accomplish these aims, we will conduct quiet-standing and dynamic posture experiments and clinical balance assessments on healthy elderly individual, diabetic patients with somatosensory deficits, and stroke patients with somatosensory deficits. This project could lead to the development of a novel bioengineering technique for improving balance control in older adults and patients with somatosensory deficits. The proposed work could thus serve to reduce the frequency, morbidity and cost of falling, and assist aged individuals and patients with somatosensory deficits in achieving maximal independence in activities of daily living and mobility. [unreadable] [unreadable]